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Weather Woes and Crops

June 1, 2001
The past 10 days or so, beginning about May 20, have brought us very poor weather for the young corn and soybean crops that are trying to get started growing in Illinois. While crops, especially in southern and eastern Illinois, have benefited greatly from the rainfall, continued cool and cloudy weather has slowed the growth of the crops and has given the crop a pale, unhealthy appearance. The corn, especially that with only three or four leaves, looks especially poor. Larger corn and just-emerging soybean plants have not been as affected, but they also don't look as healthy as we'd like.

In most fields, a few days of warm, sunny weather will produce rapid improvement in the appearance of the crop. Besides the unfortunate interruption of growth, which will delay future development of the crop, there will probably not be much lasting effect of these weather problems on the corn crop. Soybean problems have been mostly insects and diseases, both of which can be more damaging when growth rates are slow.

In some fields, though, especially in the Quad Cities area, where rainfall has been excessive (our Monmouth research center has had more than 8 inches of rain in May), some corn plants are showing more severe symptoms. We saw corn there this week that was twisted and lying on the ground, with what appeared to be growth regulator­type herbicide injury. Such herbicides had not been used, and I believe such injury symptoms come from weather conditions, including strong winds during storms, slow growth rates that retard recovery growth, lack of sunlight to "feed" photosynthesis, and cool temperatures that keep plants from re-forming the chlorophyll that has been lost. Most of these plants will recover, but where they remain "tied-in" too long, they might not survive, or they may not recover sufficiently to compete with neighboring plants. Such unevenness will probably hurt yield to some extent.

On the positive side, most plant stands are good and most root systems appear to be in good shape. These factors will be important in maintaining good yield potential in fields once the weather returns to more average conditions.--Emerson Nafziger

Author: Emerson Nafziger

The Pest Management and Crop Development Bulletin
Executive Editor: Kevin Steffey, Extension Entomologist

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